1. Field of the Invention
The present invention relates to a semiconductor substrate, a substrate inspection method, a semiconductor device manufacturing method, and an inspection apparatus.
2. Related Background Art
In an in-situ defect inspection in a hole formation process of the manufacture of a semiconductor device, a defect inspection method is used, which comprises acquiring potential contrast images of the surfaces of wiring lines present in one particular chip within the surface of a wafer and comparing the potential contrast images of the surfaces of wiring lines corresponding to the above wiring lines between adjacent cells or dies in order to detect defects of the wiring lines (e.g., Japan Society for the Promotion of Science, 132nd committee, 24th LSI testing symposium/2004, “Line monitoring method by potential contrast defect detection, P77-83”, Microlithography Proceedings of SPIE Vol. 5752(2004), pp. 997-1008/“Develoment of voltage contrast inspection technique for line monitoring 300 mm ULSI hp 90 logic contact layer”).
Defect inspection methods of this type are generally called a cell-to-cell image comparison inspection method and a die-to-die image comparison inspection method. The cell-to-cell image comparison inspection method is used to inspect a die such as a memory device having repetitive wiring lines. While the die-to-die image comparison inspection method is used to inspect a die such as a logic device having no repetitive wiring lines. Conventionally, an electron beam is irradiated to the surface of such a semiconductor device to acquire a potential contrast image, and from this image, critical defects (breaking of a wire and a short circuit of the wiring line) which present in a lower layer of the wiring line are detected by watching a difference in potential contrast in the surfaces of the wiring lines.
However, for example, in the case of a defective product having a high leak current value (leak current value: ˜E-5A) in which there is a short circuit between adjacent contact holes due to the presence of a void in an insulating film between these contact holes (hereinafter referred to as a “short between contact wiring lines”.), there is no difference of signal intensity between the image of this defective product and the image of a nondefective product, so that it is impossible for the inspection method described above to judge the short as a defect from the value of a difference between the signal intensities, causing difficulty in inspection. The reason is as follows: the contact wiring lines have direct or indirect electric conduction to a substrate at the bottoms of the contact holes even in the case of the defective product (the short between the contact wiring lines) (e.g., resistance value: 10Ω or less), and the contact wiring lines have direct or indirect electric conduction to a substrate at the bottoms of the contact holes in the comparative nondefective product as well (e.g., resistance value: 10Ω or less), so that the quantity of charges on the surfaces of the contact wiring lines is equal in the nondefective product and the defective product. As a result, the prior arts have a problem of decreased inspection accuracy.